Low molecular weight, semi-crystalline ethylene-based polymers (for example, weight average molecule weights less than 5,000 g/mole) can be used in formulations to make hot melt adhesives (for example, as wax components), and in other types of adhesives. Such polymers may be produced with conventional catalyst systems, for example, constrained geometry type catalyst systems or other bis-phenylphenoxy catalysts; however, typically significantly low polymerization temperatures are needed (<135° C.) to produce theses polymers. It is desirable to find new polymerizations using new catalyst systems, which are capable of making these low molecular weight, semi-crystalline polymers at elevated temperatures, with good efficiencies to allow for increased reactor throughput. This need has been met by the following invention.